Process to prepare a haze free base oil

ABSTRACT

Process to prepare a haze free base oil having a kinematic viscosity at 100° C. of greater than 10 cSt from a Fischer-Tropsch wax feed by performing the following steps, (a) reducing the wax content of the feed by contacting the feed with a hydroisomerisation catalyst under hydroisomerisation conditions at a remote location, (b) transporting an intermediate product having a reduced wax content as obtained in step (a) from one location to another location, and (c) solvent dewaxing the transported intermediate product to obtain the haze free base oil at the location closer to the end-user.

The invention relates to a process to prepare a haze free base oilhaving a kinematic viscosity at 100° C. of greater than 10 cSt from aFischer-Tropsch wax.

Many publications are known describing processes for the conversion ofgaseous hydrocarbonaceous feed stocks, as methane, natural gas and/orassociated gas, into liquid products, especially methanol and liquid orsolid hydrocarbons, particularly paraffinic hydrocarbons. In thisrespect often reference is made to remote locations (e.g. in thedessert, tropical rain-forest) and/or offshore locations, where nodirect use of the gas is possible, usually due to the absence of largepopulations and/or the absence of any industry. Transportation of thegas, e.g. through a pipeline or in the form of liquefied natural gas,requires extremely high capital expenditure or is simply not practical.

To make efficient use of such stranded gas reserves on-siteFischer-Tropsch processes are being build. Such processes involve asynthesis gas manufacturing step using the natural gas as feedstock anda Fischer-Tropsch synthesis step to make a heavy wax. WO-A-02070627describes a process for preparing a base oil having a kinematicviscosity at 100° C. of 22 cSt from a heavy Fischer-Tropsch wax.

A problem of the prior art processes is that especially the base oilshaving a high viscosity often show a haze. This haze makes the processless suitable for some applications. However not all applications forthis family of base oils require that a haze should be absent. Theobject of the present invention is a process to prepare haze free baseoils in an efficient manner.

The following process achieves this object. Process to prepare a hazefree base oil having a kinematic viscosity at 100° C. of greater than 10cSt from a Fischer-Tropsch wax feed by performing the following steps,

-   (a) reducing the wax content of the feed by contacting the feed with    a hydroisomerisation catalyst under hydroisomerisation conditions at    a remote location,-   (b) transporting an intermediate product having the reduced wax    content as obtained in step (a) from one location to another    location, and-   (c) solvent dewaxing the transported intermediate product to obtain    the haze free base oil at the location closer to the end-user.

The process according the invention is advantageous because step (a) istypically performed at a remote location. Thus any low boilingby-products can be advantageously be blended with lower boiling productsof the Fischer-Tropsch process at that remote location. Examples of suchproducts are base oils having a lower viscosity and gas oil. A furtheradvantage of this process is that step (c) can be performed at alocation more close to the end users. This allows the user of thisprocess to choose the dewaxing technique most suited for the specificapplication. Thus if a haze free lubricant is required a solventdewaxing step according the invention is applied. If on the other handhaze is not a major issue a less selective dewaxing technique can beused. Thus it is not required to have two types of dewaxing technologyat the remote location and optimal use can be made of existing dewaxingfacilities at the locations more close to the end users. A furtheradvantage is that all of the intermediate product can be efficientlyused. Because step (c) is a solvent dewaxing step an oil having thedesired viscometric properties and a valuable microcrystalline wax isobtained. Thus all of the intermediate product can be sold as products.In contrast, if a catalytic dewaxing is performed on the intermediateproduct low boiling by-products would have been obtained which wouldonly have a blending value at the location close to the costumer. Thisvalue would be less than the value of these by-products if the dewaxinghad been performed at the remote location. A further advantage is thatthe high quality products such as the haze free base oil as well as thewax as prepared in step (c) do not have to be transported from theremote location to the end users.

A further advantage is that the wax feed used in step (a) may alsocontain the heaviest molecules as prepared in the Fischer-Tropschsynthesis. This is advantageous because it is now possible to preparehigh viscosity grade base oils without having to perform a deep-cutdistillation in order to remove possible haze-precursors as for exampledescribed in WO-A-03033622.

The Fischer-Tropsch wax as used in step (a) can be obtained bywell-known processes, for example the so-called Sasol process, the ShellMiddle Distillate Process or by the ExxonMobil “AGC-21” process. Theseand other processes are for example described in more detail inEP-A-776959, EP-A-668342, U.S. Pat. No. 4,943,672, U.S. Pat. No.5,059,299, WO-A-9934917 and WO-A-9920720. The process will generallycomprise a Fischer-Tropsch synthesis and a hydroisomerisation step asdescribed in these publications.

More preferably the wax used in step (a) is prepared according to thefollowing process. In this process a Fischer-Tropsch product issubjecting to a hydroisomerisation step and a wax containing fraction isisolated from the product of said hydroisomerisation step. Morepreferably this fraction is a distillation residue comprising the mosthighly molecular weight compounds still present in the product of thehydroisomerisation step. The 10 wt % recovery boiling point of saidfraction is preferably above 370° C., more preferably above 400° C. andmost preferably above 500° C. for certain embodiments of the presentinvention. In case the feed to step (a) has a 10 wt % recovery boilingpoint of above 500° C. the wax content will suitably be greater than 50wt %. The feed to the hydroisomerisation step is preferably aFischer-Tropsch product which has at least 30 wt %, preferably at least50 wt %, and more preferably at least 55 wt % of compounds having atleast 30 carbon atoms. Furthermore the weight ratio of compounds havingat least 60 or more carbon atoms and compounds having at least 30 carbonatoms of the Fischer-Tropsch product is at least 0.2, preferably atleast 0.4 and more preferably at least 0.55. Preferably theFischer-Tropsch product comprises a C20+ fraction having an ASF-alphavalue (Anderson-Schulz-Flory chain growth factor) of at least 0.925,preferably at least 0.935, more preferably at least 0.945, even morepreferably at least 0.955.

The initial boiling point of the Fischer-Tropsch product may range up to400° C., but is preferably below 200° C. Preferably any compounds having4 or less carbon atoms and any compounds having a boiling point in thatrange are separated from a Fischer-Tropsch synthesis product before theFischer-Tropsch synthesis product is used in said hydroisomerisationstep.

Such a Fischer-Tropsch product can be obtained by any process, whichyields a relatively heavy Fischer-Tropsch product. Not allFischer-Tropsch processes yield such a heavy product. An example of asuitable Fischer-Tropsch process is described in WO-A-9934917 and inAU-A-698392. These processes may yield a Fischer-Tropsch product asdescribed above.

The Fischer-Tropsch product will contain no or very little sulphur andnitrogen containing compounds. This is typical for a product derivedfrom a Fischer-Tropsch reaction, which uses synthesis gas containingalmost no impurities. Sulphur and nitrogen levels will generally bebelow the detection limits, which are currently 5 ppm for sulphur and 1ppm for nitrogen.

The hydrocracking/hydroisomerisation reaction of the hydroisomerisationis preferably performed in the presence of hydrogen and a catalyst,which catalyst can be chosen from those known to one skilled in the artas being suitable for this reaction. Catalysts for use in thehydroisomerisation typically comprise an acidic functionality and ahydrogenation/dehydrogenation functionality. Preferred acidicfunctionality's are refractory metal oxide carriers. Suitable carriermaterials include silica, alumina, silica-alumina, zirconia, titania andmixtures thereof. Preferred carrier materials for inclusion in thecatalyst for use in the process of this invention are silica, aluminaand silica-alumina. A particularly preferred catalyst comprises platinumsupported on a silica-alumina carrier. Preferably the catalyst does notcontain a halogen compound, such as for example fluorine, because theuse of such catalysts require special operating conditions and involveenvironmental problems. Examples of suitablehydrocracking/hydroisomerisation processes and suitable catalysts aredescribed in WO-A-0014179, EP-A-532118, EP-A-666894 and the earlierreferred to EP-A-776959.

Preferred hydrogenation/dehydrogenation functionality's are Group VIIImetals, for example cobalt, nickel, palladium and platinum and morepreferably platinum. In case of platinum and palladium the catalyst maycomprise the hydrogenation/dehydrogenation active component in an amountof from 0.005 to 5 parts by weight, preferably from 0.02 to 2 parts byweight, per 100 parts by weight of carrier material. In case nickel isused a higher content will be present, optionally nickel is used incombination with copper. A particularly preferred catalyst for use inthe hydroconversion stage comprises platinum in an amount in the rangeof from 0.05 to 2 parts by weight, more preferably from 0.1 to 1 partsby weight, per 100 parts by weight of carrier material. The catalyst mayalso comprise a binder to enhance the strength of the catalyst. Thebinder can be non-acidic. Examples are clays and other binders known toone skilled in the art.

In the hydroisomerisation the feed is contacted with hydrogen in thepresence of the catalyst at elevated temperature and pressure. Thetemperatures typically will be in the range of from 175 to 380° C.,preferably higher than 250° C. and more preferably from 300 to 370° C.The pressure will typically be in the range of from 10 to 250 bar andpreferably between 20 and 80 bar. Hydrogen may be supplied at a gashourly space velocity of from 100 to 10000 Nl/l/hr, preferably from 500to 5000 Nl/l/hr. The hydrocarbon feed may be provided at a weight hourlyspace velocity of from 0.1 to 5 kg/l/hr, preferably higher than 0.5kg/l/hr and more preferably lower than 2 kg/l/hr. The ratio of hydrogento hydrocarbon feed may range from 100 to 5000 Nl/kg and is preferablyfrom 250 to 2500 Nl/kg.

The conversion in the hydroisomerisation as defined as the weightpercentage of the feed boiling above 370° C. which reacts per pass to afraction boiling below 370° C., is at least 20 wt %, preferably at least25 wt %, but preferably not more than 80 wt %, more preferably not morethan 70 wt %. The feed as used above in the definition is the totalhydrocarbon feed fed to the hydroisomerisation, thus also any optionalrecycle to step (a).

One or more distillate separations are performed on the effluent of thehydroisomerisation step to obtain at least one middle distillate fuelfraction and the wax which is to be used in step (a). Preferably theeffluent is subjected to an atmospheric distillation. The residue asobtained in such a distillation may in certain preferred embodiments besubjected to a further distillation performed at near vacuum conditionsto arrive at a fraction having a higher 10 wt % recovery boiling point.Thus the 10 wt % recovery boiling point of the residue may preferablyvary between 350 and 550° C. This atmospheric bottom product or residuepreferably boils for at least 95 wt % above 370° C. This fraction may bedirectly used in step (a) or may be subjected to an additional vacuumdistillation suitably performed at a pressure of between 0.001 and 0.1bara. The heavy wax for step (a) is preferably obtained as the bottomproduct of such a vacuum distillation.

Step (a) may be performed using any hydroconversion process, which iscapable of reducing the wax content. to below 50 wt %. The wax contentin the intermediate product is preferably below 35 wt % and morepreferably between 5 and 35 wt %, and even more preferably between 10and 35 wt %. A minimal amount of wax will is required in order tooperate a solvent dewaxing step in an optimal manner. The intermediateproduct as obtained in step (a) preferably has a congealing point ofbelow 80° C. and more preferably between 20 and 60° C. Preferably morethan 50 wt % and more preferably more than 70 wt % of the intermediateproduct boils above the 10 wt % recovery point of the wax feed used instep (a). The wax content as used in the description is measuredaccording to the following procedure. 1 weight part of the to bemeasured oil fraction is diluted with 4 parts of a (50/50 vol/vol)mixture of methyl ethyl ketone and toluene, which is subsequently cooledto −20° C. in a refrigerator. The mixture is subsequently filtered at−20° C. The wax is thoroughly washed with cold solvent, removed from thefilter, dried and weighed. If reference is made to oil content a wt %value is meant which is 100% minus the wax content in wt %.

A possible process is the hydroisomerisation process as described above.It has been found that the wax may be reduced to the desired level usingsuch catalyst. By varying the severity of the process conditions asdescribed above a skilled person will easily determine the requiredoperating conditions to arrive at the desired wax conversion. However atemperature of between 300 and 330° C. and a weight hourly spacevelocity of between 0.1 and 5, more preferably between 0.1 and 3 kg ofoil per litre of catalyst per hour (kg/l/hr) are especially preferredfor optimising the oil yield.

A more preferred class of catalyst, which may be applied in step (a), isthe class of dewaxing catalysts. The process conditions applied whenusing such catalysts should be such that a wax content remains in theoil. In contrast typical catalytic dewaxing processes aim at reducingthe wax content to almost zero. Using a dewaxing catalyst comprising amolecular sieve will result in that more of the heavy molecules areretained in the dewaxed oil. Thus a more viscuous base oil can then beobtained.

The dewaxing catalyst which may be applied in step (a) suitablycomprises a molecular sieve and optionally in combination with a metalhaving a hydrogenation function, such as the Group VIII metals.Molecular sieves, and more suitably molecular sieves having a porediameter of between 0.35 and 0.8 nm have shown a good catalytic abilityto reduce the wax content of the wax feed. Suitable zeolites aremordenite, beta, ZSM-5, ZSM-12, ZSM-22, ZSM-23, SSZ-32, ZSM-35 andZSM-48 or combinations of said zeolites. Another preferred group ofmolecular sieves are the silica-aluminaphosphate (SAPO) materials ofwhich SAPO-11 is most preferred as for example described in U.S. Pat.No. 4,859,311. ZSM-5 may optionally be used in its HZSM-5 form in theabsence of any Group VIII metal. The other molecular sieves arepreferably used in combination with an added Group VIII metal. SuitableGroup VIII metals are nickel, cobalt, platinum and palladium. Examplesof possible combinations are Pt/ZSM-35, Ni/ZSM-5, Pt/ZSM-23, Pd/ZSM-23,Pt/ZSM-48 and Pt/SAPO-11 or stacked configurations of Pt/zeolite betaand Pt/ZSM-23, Pt/zeolite beta and Pt/ZSM-48 or Pt/zeolite beta andPt/ZSM-22. Further details and examples of suitable molecular sieves anddewaxing conditions are for example described in WO-A-9718278, U.S. Pat.No. 4,343,692, U.S. Pat. No. 5,053,373, U.S. Pat. No. 5,252,527,US-A-20040065581, U.S. Pat. No. 4,574,043 and EP-A-1029029.

A preferred class of molecular sieves are those having a relatively lowisomerisation selectivity and a high wax conversion selectivity, likeZSM-5 and ferrierite (ZSM-35).

The dewaxing catalyst suitably also comprises a binder. The binder canbe a synthetic or naturally occurring (inorganic) substance, for exampleclay, silica and/or metal oxides. Natural occurring clays are forexample of the montmorillonite and kaolin families. The binder ispreferably a porous binder material, for example a refractory oxide ofwhich examples are: alumina, silica-alumina, silica-magnesia,silica-zirconia, silica-thoria, silica-beryllia, silica-titania as wellas ternary compositions for example silica-alumina-thoria,silica-alumina-zirconia, silica-alumina-magnesia andsilica-magnesia-zirconia. More preferably a low acidity refractory oxidebinder material, which is essentially free of alumina, is used. Examplesof these binder materials are silica, zirconia, titanium dioxide,germanium dioxide, boria and mixtures of two or more of these of whichexamples are listed above. The most preferred binder is silica.

A preferred class of dewaxing catalysts comprise intermediate zeolitecrystallites as described above and a low acidity refractory oxidebinder material which is essentially free of alumina as described above,wherein the surface of the aluminosilicate zeolite crystallites has beenmodified by subjecting the aluminosilicate zeolite crystallites to asurface dealumination treatment. A preferred dealumination treatment isby contacting an extrudate of the binder and the zeolite with an aqueoussolution of a fluorosilicate salt as described in for example U.S. Pat.No. 5,157,191 or WO-A-0029511. Examples of suitable dewaxing catalystsas described above are silica bound and dealuminated Pt/ZSM-5, silicabound and dealuminated Pt/ZSM-35 as for example described inWO-A-0029511 and EP-B-832171.

The conditions in step (a) when using a dewaxing catalyst typicallyinvolve operating temperatures in the range of from 200 to 500° C.,suitably from 250 to 400° C. Preferably the temperature is between 300and 330° C. The hydrogen pressures in the range of from 10 to 200 bar,preferably from 40 to 70 bar, weight hourly space velocities (WHSV) inthe range of from 0.1 to 10 kg of oil per litre of catalyst per hour(kg/l/hr), suitably from 0.1 to 5 kg/l/hr, more suitably from 0.1 to 3kg/l/hr and hydrogen to oil ratios in the range of from 100 to 2,000litres of hydrogen per litre of oil.

Transportation in step (b) is preferably performed by means of a ship.The location at which step (a) is performed is preferably a remotelocation and the location of which step (c) is performed is preferably alocation more close to the end users of the base oil. The product isloaded into the ships containers by preferably first purging the emptyproduct containers in the ship with nitrogen in order to lower theoxygen content. Purging is preferably performed for at least 5 minutesand more preferably for at least 10 minutes. After purging the productcontainers are filled with the intermediate product. Preferably nitrogenis supplied to the loaded containers to achieve a nitrogen atmosphere inthe gaseous space above the product in the product containers. Morepreferably nitrogen is supplied for at least 5 minutes and morepreferably for at least 10 minutes to the loaded containers. Theduration of the transport in step (b) is typically more than 5 days. Thenitrogen used is preferably the nitrogen as obtained when oxygen isisolated from the air in an air separation unit. The oxygen is typicallyused to prepare synthesis gas, which in turn in used as feedstock forthe Fischer-Tropsch reaction to make the F-T wax.

In step (c) the haze free oil is obtained by solvent dewaxing theintermediate product as transported in step (b). Solvent dewaxing iswell known to those skilled in the art and involves admixture of one ormore solvents and/or wax precipitating agents with the base oilprecursor fraction and cooling the mixture to a temperature in the rangeof from −10° C. to −40° C., preferably in the range of from −20° C. to−35° C., to separate the wax from the oil. The oil containing the wax isusually filtered through a filter cloth which can be made of textilefibres, such as cotton; porous metal cloth; or cloth made of syntheticmaterials. Examples of solvents which may be employed in the solventdewaxing process are C₃-C₆ ketones (e.g. methyl ethyl ketone, methylisobutyl ketone and mixtures thereof), C₆-C₁₀ aromatic hydrocarbons(e.g. toluene), mixtures of ketones and aromatics (e.g. methyl ethylketone and toluene), autorefrigerative solvents such as liquefied,normally gaseous C₂-C₄ hydrocarbons such as propane, propylene, butane,butylene and mixtures thereof. Mixtures of methyl ethyl ketone andtoluene or methyl ethyl ketone and methyl isobutyl ketone are generallypreferred. Examples of these and other suitable solvent dewaxingprocesses are described in Lubricant Base Oil and Wax Processing,Avilino Sequeira, Jr, Marcel Dekker Inc., New York, 1994, Chapter 7.

In step (c) also a wax is obtained. It has been found that such a wax isa relatively soft microcrystalline wax, which may be used for variouspurposes. An additional advantage of the present invention is that thewax is recovered from the intermediate product at a location near theend-costumer. The soft microcrystalline wax as obtained with the aboveprocess has preferably a congealing point as determined by ASTM D 938 ofbetween 85 and 120 and more preferably between 95 and 120° C. and a PENat 43° C. as determined by IP 376 of more than 0.8 mm and preferablymore than 1 mm. The wax is further characterized in that it preferablycomprises less than 1 wt % aromatic compounds and less than 10 wt %naphthenic compounds, more preferably less than 5 wt % naphtheniccompounds. The mol percentage of branched paraffins in the wax ispreferably above 33 and more preferably above 45 and below 80 mol % asdetermined by C₁₃ NMR. This method determines an average molecularweight for the wax and subsequently determines the mol percentage ofmolecules having a methyl branch, the mol percentage of molecules havingan ethyl branch, the mol percentage of molecules having a C₃ branch andthe mol percentage having a C₄+ branch, under the assumption that eachmolecule does not have more than one branch. The mol % of branchedparaffins is the total of these individual percentages. This methodcalculated the mol % in the wax of an average molecule having only onebranch. In reality paraffin molecules having more than one branch may bepresent. Thus the content of branched paraffins determined by adifferent method than above may result in a different value.

The oil content of the wax as determined by ASTM D 721 is typicallybelow 10 wt % and more preferably below 6 wt %. If lower oil contentsare desired it may be advantageous to perform an additional de-oilingstep. De-oiling processes are well known and are for example describedin Lubricant Base Oil and Wax Processing, Avilino Sequeira, Jr, MarcelDekker Inc., New York, 1994, pages 162-165. After de-oiling the waxpreferably has a oil content of between 0.1 and 2 wt %. The lower limitis not critical. Values of above 0.5 wt % may be expected, but lowervalues can be achieved depending on the method in which the wax isobtained. Most likely the oil content will be between 1 and 2 wt %. Thekinematic viscosity at 150° C. of the wax is preferably higher than 8cSt and more preferably higher than 12 and lower than 18 cSt.

The haze free base oil will preferably have a kinematic viscosity at100° C. of above 10 cSt, preferably above 14 cSt which viscosity mayrange up to 30 cSt and even above. The pour point is preferably below−5° C., more preferably below −18° C. and even more preferably below−21° C. The viscosity index is suitably above 120 and preferably above130. A haze free base oil is determined by its cloud point. A haze freebase oil according to this invention has a cloud point as determined byASTM D2500 of near the pour point and below 0° C., preferably below −10°C. and more preferably below −15° C.

Because of these properties applicant has found that the base oil may beadvantageously be used to prepare a lubricant composition which does notrequire a viscosity modifier (VM). Applicants further found that such aVISCOSITY MODIFIER-free lubricant may be obtained without having to adda poly-alpha olefin co-base oil as shown in WO-A-0157166. The inventionis thus also directed to prepare a VM-free lubricant composition byblending a preferably Fischer-Tropsch derived and low viscosity base oilwith the haze free base oil as obtained in step (c) and one or moreadditives. The low viscosity base oil preferably has a kinematicviscosity at 100° C. of less than 7 cSt. The haze free base oilpreferably has a kinematic viscosity at 100° C. of more than 10 cSt,more preferably more than 14 cSt and most preferably more than 18 cSt.

Applicants found that by blending the haze free base oil with the lowerviscosity grade base oil it is possible to achieve the properties of aso-called SAE “xW-y” viscosity lubricant formulation without having toadd a viscosity modifier. Applicants further found that when a viscositymodifier-free lubricant is used as motor engine lubricant in gasolinedirect injection (GDI) engines no build up of residue on the back of theinlet valve tulip occurs, which would happen if a VM is present.

It has further been found that especially SAE “xW-y” viscosity lubricantformulations wherein y minus x is greater or equal than 25 can beprepared without having to add a VM. Based on the teaching ofWO-A-0157166 one would have expected that such formulations could onlybe prepared by having to add a VM.

The low viscosity Fischer-Tropsch derived base oil having a kinematicviscosity at 100° C. of less than 7 cSt preferably has a pour point ofless than −18° C., more preferably less than −27° C. The kinematicviscosity at 100° C. is preferably greater than 3.5 cSt and morepreferably between 3.5 and 6 cSt. The viscosity index (VI) is preferablygreater than 120, more preferably greater than 130. The VI willtypically be less than 160. The Noack volatility (according to CEC L40T87) is preferably less than 14 wt %. The low viscosity component may bea typical API Group III base oil and more preferably a Fischer-Tropschderived base oil as disclosed in for example EP-A-776959, EP-A-668342,WO-A-9721788, WO-A-0015736, WO-A-0014188, WO-A-0014187, WO-A-0014183,WO-A-0014179, WO-A-0008115, WO-A-9941332, EP-A-1029029, WO-A-0118156 andWO-A-0157166.

EXAMPLE 1

From a hydroisomerised Fischer-Tropsch wax a distillation residue wasisolated having the properties as listed in Table 1. The wax content was34.1 wt % as determined after solvent dewaxing at a dewaxing temperatureof −20° C. TABLE 1 Feed to catalytic dewaxing Congealing Point ° C. >+48Density at 70° C. 0.7874 IBP % m distilled ° C. 261 10 ° C. 346 50 ° C.482 70 ° C. 564 90 ° C. 665 FBP ° C. >750

The above residue was contacted with a dewaxing catalyst consisting of0.7 wt % platinum, 25 wt % ZSM-12 and a silica binder. The dewaxingconditions were 40 bar hydrogen, WHSV=1 kg/l.h, and a hydrogen gas rateof 500 Nl/kg feed. The experiment was carried out at three differentreaction temperatures. See results in TABLE 2 1a 1b 1c Temperature indewaxing 325 310 300 reactor (° C.) Yield of fraction 34 45 48 boilingabove 485° C. by TBP-GLC (wt % on feed) Wax content of the 7.1 34.8 56.3fraction boiling above 485° C. (wt %)* Constitution of the Liquid liquidSolid at intermediate product at room slurry room tempera- tempera- tureturewax content as measured after solvent dewaxing at −20° C.

The fraction boiling above 485° C. as obtained in 1 a, 1 b and 1 c waseasy to transport. Optionally the fraction to be transported could alsocomprise the liquid fraction boiling below 485° C. as obtained in thecatalytic dewaxing step. The transportable intermediate product wassubsequently solvent dewaxed using a mixture of methyl ethyl ketone andtoluene (50/50 vol/vol) solvent at a dewaxing temperature of −20° C. Theproperties and yields of the oils obtained are listed in Table 3. TABLE3 Oil Properties 1a 1b 1c Base oil yield 31 24 21 relative to feed tothe catalytic dewaxing step (wt %) Clarity of the base Excellent GoodBad oil density 70/4 of the 0.8026 0.8021 0.7997 base oil Pour Point ofthe base −42 −15 −9 oil (° C.) Vk @ 40° C. (mm²/s) 120.6 112.6 Notmeasured Vk @ 100° C. (mm²/s) 16.32 16.1 13.47 VI 145 143 Not measured

Based on the above experimental data FIG. 1 was made. In FIG. 1 it isshown that by increasing the catalytic dewaxing severity the yield tothe 485° C. plus fraction decreases, the wax content decreases and theoil yield after solvent dewaxing goes through a maximum.

EXAMPLE 2

From a hydroisomerised Fischer-Tropsch wax a distillation residue wasisolated having the properties as listed in Table 4. The wax content was41 wt % as determined after solvent dewaxing at a dewaxing temperatureof −20° C. TABLE 4 Feed to catalytic dewaxing Congealing Point ° C. >+85IBP % m distilled ° C. 440 10 ° C. 500 50 ° C. 595 70 ° C. 655 90 ° C.740 FBP ° C. >740

The above residue was contacted with a dewaxing catalyst consisting of0.7 wt % platinum, 25 wt % ZSM-12 and a silica binder. The dewaxingconditions were 40 bar hydrogen, WHSV=1 kg/l.h, and a hydrogen gas rateof 500 Nl/kg feed. The experiment was carried out at 340° C. From thepartly dewaxed oil compounds boiling below 500° C. were removed bydistillation. The remaining fraction containing 34 wt % wax was a liquidslurry at room temperature and was thus easy to transport. See also theresults in Table 5. TABLE 5 Example 2 Temperature in dewaxing 340reactor (° C.) Yield of fraction boiling 68 above 500° C. by TBP-GLC (wt% on feed) Wax content of the fraction 34 boiling above 500° C. (wt %)**wax content as measured after solvent dewaxing at −20° C.

The liquid slurry fraction boiling above 500° C. was solvent dewaxedusing a mixture of methyl ethyl ketone and toluene (50/50 vol/vol)solvent at a dewaxing temperature of −20° C. The properties and yieldsof the oil as obtained are listed in Table 6. TABLE 6 Oil Properties 2Base oil yield 42 relative to feed to the catalytic dewaxing step (wt %)Clarity of the base Clear oil Density 20/4 of the 0.8331 base oil PourPont of the base −39 oil (° C.) Vk @ 40° C. (mm²/s) 111.6 Vk @ 100° C.(mm²/s) 15.47 VI 146

1. A process to prepare a haze free base oil having a kinematicviscosity at 100° C. of greater than 10 cSt from a Fischer-Tropsch waxfeed comprising the following steps: (a) reducing the wax content of aFischer-Tropsch wax feed by contacting the feed with ahydroisomerisation catalyst under hydroisomerisation conditions at aremote location to form an intermediate product; (b) transporting theintermediate product having the reduced wax content as obtained in step(a) from the remote location to another location closer to the end-user;and (c) solvent dewaxing the transported intermediate product to obtainthe a haze free base oil at the location closer to the end-user.
 2. Theprocess according to claim 1, wherein the feed to step (a) has a 10 wt %recovery boiling point of above 500° C. and a wax content of greaterthan 50 wt %.
 3. The process according to claim 2, wherein the waxcontent in the feed is between 60 and 95 wt %.
 4. The process accordingto claim 2, wherein the 10 wt % recovery boiling point of the feed isbetween 500 and 550° C.
 5. The process according to claim 1, wherein thewax content in the intermediate product is between 10 and 35 wt %. 6.The process according to claim 1, wherein the intermediate product has acongealing point of between 20 and 60° C.
 7. The process according toclaim 1, wherein more than 50 wt % of the intermediate product boilsabove the 10 wt % recovery point of the feed used in step (a).
 8. Theprocess according to claim 7, wherein more than 70 wt % of theintermediate product boils above the 10 wt % recovery point of the feedused in step (a).
 9. The process according to claim 1, wherein thehydroisomerisation catalyst used in step (a) is a substantiallyamorphous based catalyst comprising a silica-alumina carrier and a nobleor non-noble Group VIII metal.
 10. The process according to claim 1,wherein the hydroisomerisation catalyst used in step (a) is a molecularsieve based catalyst and a noble or non-noble Group VIII metal.
 11. Theprocess according to claim 1, wherein step (b) is performed by means ofa ship and wherein containers on the ship are first purged with nitrogenbefore loading and wherein the nitrogen is obtained in an air-separationunit which unit also isolates oxygen for use to make syngas which inturn is used as feedstock to prepare the Fischer-Tropsch wax feed.
 12. Aprocess to prepare a lubricant composition not containing a viscositymodifier additive by blending a low viscosity base oil with a haze freebase oil having a kinematic viscosity at 100° C. of greater than 10 cStfrom a Fischer-Tropsch wax feed prepared by a process comprising thefollowing steps: (a) reducing the wax content of a Fischer-Tropsch waxfeed by contacting the feed with a hydroisomerisation catalyst underhydroisomerisation conditions at a remote location to form anintermediate product; (b) transporting the intermediate product havingthe reduced wax content as obtained in step (a) from the remote locationto another location closer to the end-user; and (c) solvent dewaxing thetransported intermediate product to obtain a haze free base oil at thelocation closer to the end-user.
 13. The process according to claim 12,wherein the feed to step (a) has a 10 wt % recovery boiling point ofabove 500° C. and a wax content of greater than 50 wt %.
 14. The processaccording to claim 12, wherein the wax content in the feed is between 60and 95 wt %.
 15. The process according to claim 12, wherein the 10 wt %recovery boiling point of the feed is between 500 and 550° C.
 16. Theprocess according to claim 12, wherein the wax content in theintermediate product is between 10 and 35 wt %.
 17. The processaccording to claim 12, wherein the intermediate product has a congealingpoint of between 20 and 60° C.
 18. The process according to claim 12,wherein more than 50 wt % of the intermediate product boils above the 10wt % recovery point of the feed used in step (a).
 19. The processaccording to claim 12, wherein more than 70 wt % of the intermediateproduct boils above the 10 wt % recovery point of the feed used in step(a).
 20. The process according to claim 12, wherein thehydroisomerisation catalyst used in step (a) is a substantiallyamorphous based catalyst comprising a silica-alumina carrier and a nobleor non-noble Group VIII metal.
 21. The process according to claim 12,wherein the hydroisomerisation catalyst used in step (a) is a molecularsieve based catalyst and a noble or non-noble Group VIII metal.
 22. Theprocess according to claim 12, wherein step (b) is performed by means ofa ship and wherein containers on the ship are first purged with nitrogenbefore loading and wherein the nitrogen is obtained in an air-separationunit which unit also isolates oxygen for use to make syngas which inturn is used as feedstock to prepare the Fischer-Tropsch wax feed.